Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/c2a75dc08b6c
Author: evanxd <itoyxd@gmail.com>
Desc: Merge pull request #20964 from evanxd/bug-1029254

Bug 1029254 - [Calendar] Tag marker says stationary as you scroll in calendar event r=mmedeiros

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https://hg.mozilla.org/integration/gaia-central/rev/6ca32594438b
Author: Evan Xd <itoyxd@gmail.com>
Desc: Bug 1029254 - [Calendar] Tag marker says stationary as you scroll in calendar event r=mmedeiros
Bumping manifests a=b2g-bump